Modular lighting panel

ABSTRACT

Systems and methods described herein provide examples of an electrical panel (e.g., a modular electrical panel) that is configured to control a plurality of electrical loads. The electrical panel may include a control circuit, memory, a communication circuit, and an alternating current (AC) line feed and/or a direct current (DC) line feed. The electrical panel may also include a plurality of power supplies and a plurality of control modules, where more than one control module is associated with each of the plurality of power supplies. Each control module may configured to receive DC power from the associated power supply and provide an output voltage to at least one electrical load. The electrical panel provides flexibility as to whether each stage of conversion, regulation, and/or control is performed at a control module located within the electrical panel or performed at an accessory module located at an electrical load.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/457,962, filed Jun. 29, 2019 (now U.S. Pat. No. 10,342,100), which isa divisional of U.S. patent application Ser. No. 15/656,437, filed Jul.21, 2017, now U.S. Pat. No. 10,548,202, which claims the benefit ofProvisional U.S. Patent Application No. 62/365,773, filed Jul. 22, 2016,the disclosures of which are incorporated herein by reference in theirentireties.

BACKGROUND

Light-emitting diode (LED) light sources (i.e., LED light engines) areoften used in place of or as replacements for conventional incandescent,fluorescent, or halogen lamps, and the like. LED light sources maycomprise a plurality of light-emitting diodes mounted on a singlestructure and provided in a suitable housing. LED light sources aretypically more efficient and have longer operational lives as comparedto incandescent, fluorescent, and halogen lamps. In order to illuminateproperly, an LED driver control device (i.e., an LED driver) may becoupled to the LED light source for regulating the power supplied to theLED light source. The LED driver may regulate either the voltageprovided to the LED light source, the current supplied to the LED lightsource, or both. Examples of LED drivers are described in greater detailin commonly-assigned U.S. Pat. No. 8,492,987, issued Jul. 23, 2010, andU.S. Patent Application Publication No. 2013/0063047, published Mar. 14,2013, both entitled LOAD CONTROL DEVICE FOR A LIGHT-EMITTING DIODE LIGHTSOURCE, the entire disclosures of which are hereby incorporated byreference in their entirety.

As the electrical infrastructure changes to accommodate renewable energysources (e.g., wind power, photovoltaic solar power, fuel cells, etc.),it is likely that there will be a movement towards direct current (DC)power distribution as this is the native version of generation for manyof these technologies. For example, photovoltaic solar arrays generateDC power and often this is directly stored in batteries. From there,power may be drawn directly from the battery bank as direct current(DC), or it may be inverted to alternating current for use byappliances. With this anticipated move to a DC power bank, it would bedesirable to use power directly as DC power rather than convert it to ACpower. Many AC electrical loads actually require DC power to functionand traditionally require rectification to render the AC power useful tothe electrical load. Many AC electrical loads also employ active powerfactor correction (PFC) so as to minimize production of unwantedharmonics on the AC mains. However, the rectification and active powerfactor correction operations introduce an efficiency loss.

Finally, existing electrical panels (e.g., lighting panels) typicallyinclude only a minimum amount of hardware for controlling the operationof the electrical load, with most, if not all, of the power conversionand load control functionality residing remote from the panel at theelectrical load. For example, electrical panels typically provide ACmains voltage to attached electrical loads, and the electrical loadstypically include the required processors, converters, and controlsnecessary to convert the received AC mains voltage into appropriatedriving voltages for the electrical loads. For instance, typical lightfixtures include not only the light emitting elements themselves, butalso the hardware and software (e.g., LED driver, ballast, etc.)required to convert the received AC mains voltage into a driving voltagefor the lighting load. This tends to result in expensive and bulkylighting fixtures.

SUMMARY

Systems and methods described herein provide examples of a load controlsystem that includes an electrical panel (e.g., a modular electricalpanel), where the electrical panel is configured to control a pluralityof electrical loads. The electrical panel may include a control circuit,memory, and a communication circuit. The electrical panel may includeone or more of an alternating current (AC) line feed, a direct current(DC) line feed, or a battery bank feed. The AC line feed may beconnected to an AC power source, while the DC line feed may be connectedto a DC power source (e.g., one or more alternative energy devices, suchas, but not limited to: a photovoltaic (PV) system, a wind turbinesystem, a hydroelectric system, etc.), and the battery bank feed may beconnected to a bank of batteries. The electrical panel may be, forexample, a lighting panel, and the plurality of electrical loads mayinclude at least lighting loads (e.g., LED light engines). Theelectrical panel may be, for example, a shading panel, and the pluralityof electrical loads may include at least motorized window treatments.

The electrical panel may also include a plurality of power supplies anda plurality of control modules, where more than one control module maybe associated with each of the plurality of power supplies. Each powersupply may be configured to receive AC power and provide DC power, whileone or more of the power supplies may also be configured to receive DCinput and output a converted version of the received DC power. Eachcontrol module may be configured to receive DC power from an associatedpower supply and provide an output voltage to at least one electricalload. The control module may provide an output voltage that is regulatedto provide power for operation and control of an associated electricalload, or the control module may provide an output voltage that is thenreceived by an accessory module at the electrical load, where theaccessory module performs the final stages of regulation and/or controlfor powering the electrical load. As such, the electrical panel providesflexibility as to whether each stage of conversion, regulation, and/orcontrol is performed at a control module located within the electricalpanel, or performed at an accessory module located at an electricalload.

The electrical panel may be configured to provide DC power from thebattery bank feed to at least one electrical load during an emergencysituation, for example, thereby eliminating the need for local and/ordedicated batteries to be located at the electrical load for emergencypower. The electrical panel may further comprise a grid-tie inverter,which may provide for an electrical connection from the DC line feed(e.g., and in turn a DC power source) to the AC line feed (e.g., and inturn an AC electrical grid). As such, the control circuit of theelectrical panel may be configured to feed DC power to an electricalgrid via the AC line feed. Further, the control circuit may beconfigured to determine whether to provide, to at least one powersupply, AC power from the AC line feed or DC power from the DC linefeed, for example, based on one or more factors described herein (e.g.,time-of-day pricing of AC power from the electrical grid).

One or more of the power supplies may be multi-feed power supplies. Forexample, one or more of the power supplies may be configured to operatean electrical load when receiving AC power from the AC line feed usingan AC input on the power supply, and configured to operate theelectrical load when receiving DC power from the DC line feed using a DCinput on the power supply. Control modules may be configured to outputdifferent Classes of power (e.g., Low Voltage Class 2, Low Voltage Class1, High Voltage Class 1, etc.). For example, a first control module maybe configured to output a first Class of power, and a second controlmodule may be configured to output a second Class of power, the secondClass being different from the first Class. Further, one or more of thepower supplies may be configured to determine whether they are operatinga Low Power Class 2 power supply, a Low Power Class 1 power supply, or aHigh Power Class 1 power supply, based on one or more of a measuredcurrent on a link to the electrical load, a measured voltage on a linkto the electrical load, a measured power on a link to the electricalload, or feedback from the electrical load.

One or more of the control modules may be configured to provide DC powerand communications over a two-wire link to an electrical load. Forexample, a control module may be configured to provide communications byinjecting a timing window within a DC voltage, the timing window beingcharacterized by one of four offsets, where each offset corresponds to adifferent data transmission (e.g., “00”, “01”, “10”, or “11”).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified block diagram of an example load control system.

FIG. 2 is a simplified block diagram of an example power supply andcontrol module of the load control system of FIG. 1.

FIG. 3 is a simplified block diagram of an example forward converter andcurrent sense circuit of the control module of FIG. 2.

FIG. 4 is an example of a timing diagram of a DC voltage generated by acontrol module of a lighting panel for communicating digital messages toan electrical load.

FIG. 5 is an example flowchart of a classification detection procedureperformed by an electrical panel.

FIG. 6 is an example of a grid-tie inverter control procedure performedby an electrical panel

DETAILED DESCRIPTION

FIG. 1 is a simplified block diagram of an example load control system100. The load control system 100 may comprise an electrical panel (e.g.,a lighting panel 102) and one or more electrical loads. The lightingpanel 102 may include a panel control circuit 104 (e.g., a panelcontroller), memory 105, a communication circuit 106, a lighting panelpower supply 107, one or more power supplies (e.g., AC/DC powerconverters), and one or more control modules. The electrical loads mayinclude one or more lighting loads, such as, but not limited to, LEDlight engines 150 and one or more motorized window treatments 160.Accordingly, the lighting panel 102 may provide power and control for aplurality of different types of electrical loads.

The lighting panel 102 may control the amount of power delivered to anelectrical load, such as an LED light engine 150, and thus the intensityof the light engine. An LED light engine 150 may include a single LED ora plurality of LEDs connected in series, in parallel, or in a suitablecombination thereof, depending on the particular lighting system. An LEDlight engine 150 may comprise one or more organic light-emitting diodes(OLEDs). The LED light engine 150 may also include a resistor and/or lowdropout regulator (LDR) that regulates/offsets the current through theLEDs.

The motorized window treatments 160 may each comprise, for example, acellular shade, a roller shade, a drapery, a Roman shade, a Venetianblind, a Persian blind, a pleated blind, a tensioned roller shadesystem, or other suitable motorized window covering. The motorizedwindow treatments 160 may each comprise a motor drive unit (not shown)for adjusting the position of a covering material of the motorizedwindow treatment 160, for example, to control the amount of daylightentering the space. The motor drive unit of each motorized windowtreatment 160 may be configured to receive digital messages via wired orwireless signals and to control the amount of daylight entering thespace in response to the received digital messages. The motorized windowtreatments 160 may each have an antenna mounted for receiving radiofrequency (RF) signals. The motor drive unit of each motorized windowtreatment 160 may receive power from an external DC power supply.

The lighting panel 102 may include input terminals for an AC line feed132, a DC line feed 134, and/or a battery bank feed 133 providing powerto the lighting panel 102. For example, the lighting panel 102 mayreceive power from the AC line feed 132 that may provide a three-phaseAC mains input voltage from an AC power source (not shown). The AC linefeed 132 may receive the AC input voltage via a main breaker or directlyfrom the grid. Alternatively, or additionally, the lighting panel 102may receive power from the DC line feed 134 and/or the battery bank feed133 that may provide a DC input voltage from a DC power source (notshown). For example, the DC power source may include one or morealternative energy devices, such as, but not limited to: a photovoltaic(PV) system, a wind turbine system, a hydroelectric system, etc. The DCpower source may also include a battery bank. If the lighting panel 102is connected to both an AC power source and a DC power source, the panelcontrol circuit 104 may be configured to determine how much power toreceive (i.e., draw) from the AC power supply, and how much power toreceive from the DC power supply, based on one or more factors (e.g.,variables), such as time-of-day pricing (e.g., of the AC power supply),availability of power from either supply, external conditions (e.g.,environmental conditions, price index, time of day, etc.), and/or thelike.

The lighting panel 102 may include a portion or the entirety of each ofa plurality of load control devices (e.g., where a load control devicemay include a combination of a power supply and a control module). Ininstances where the lighting panel 102 includes a portion of a loadcontrol device, the remaining portions may reside remote from thelighting panel 102 (e.g., at the electrical load). For example, thelighting panel 102 may include various parts or stages of an LED driverused to control an LED light engine. The lighting panel 102 may includeone or more LED drivers in their entirety and/or one or more varyingportions of other LED drivers. As such, the lighting panel 102 may bemodular and include select stages of power conversion and control (e.g.,dimming control) in the lighting panel 102 itself for each of aplurality of electrical loads and electrical load types. For example,expensive and/or complicated control techniques (e.g., power conversiontechniques aimed at reducing switching loss) may be implemented in thelighting panel 102 to reduce the costs and/or complexity of theindividual light fixtures (and in turn the entire light control system100). The lighting panel 102 may output DC power to at least some of theconnected electrical loads, and as such, provide for DC powerdistribution (e.g., versus AC power distribution) from the panel to theloads. The example lighting panel 102 of FIG. 1 is just one of manyconfigurations that may be taken by the lighting panel 102.

The lighting panel 102 may include one or more power supplies and one ormore control modules. The power supplies may perform power conversion(e.g., from an AC input to a DC output) and/or power factor correction(PFC) to adjust the power factor towards a power factor of one. Forexample, the power supplies may each include an AC/DC converter and aPFC circuit. The AC/DC converter may be in the form of a rectifiercircuit. Alternatively, the power supply may not include an AC/DCconverter (e.g., a rectifier circuit), for example, if the power supplyis connected to the DC line feed 134 and not the AC line feed 132. ThePFC circuit may include a boost converter, a buck converter, abuck-boost converter, a flyback converter, a linear regulator, or acombination of a switching regulator and a linear regulator. The boostconverter of the power supply may receive a rectified voltage V_(RECT)and generate a boosted DC bus voltage V_(BUS) across a bus capacitorC_(BUS) (e.g., an electrolytic capacitor). The power supply may providethe DC bus voltage V_(BUS) to one or more control modules. The powersupply and the control modules may also communicate with one anotherover the DC bus (e.g., in accordance with the communication protocoldescribed with reference to FIG. 4). A power supply may include adedicated control circuit or be entirely controlled by the panel controlcircuit 104 of the lighting panel 102.

The lighting panel 102 may include a plurality of different powersupplies that output a plurality of different power-limited DC busvoltages V_(BUS) (e.g., 100 W limited, 500 W limited, 750 W limited,4,500 W limited, and/or the like). The power supplies may include theirown control circuit (e.g., microprocessor, an application-specificintegrated circuit (ASIC), or analog IC) and/or use the panel controlcircuit 104 of the lighting panel 102. Further, the power supplies mayinclude a radio-frequency interference (RFI) filter circuit thatminimizes RF noise on the AC mains or the DC mains. The power suppliesmay also include snubbing circuits that reduce switching losses of theAC/DC converters, such as lossless snubbers. Further, when not in use,the power supplies may reside in a sleep state (e.g., when the powersupply comprises its own control circuit) or a complete off state (e.g.,when the power supply does not include its own control circuit and usesthe panel control circuit 104 of the lighting panel 102).

The lighting panel 102 may, for example, include AC/DC power supplies,such as an AC/DC power supply 108, an AC/DC power converter 110, and/oran AC/DC power converter 112. The AC/DC power supplies may receive ACline voltage from the AC line feed 132. The AC/DC power supplies mayoutput DC power (e.g., the DC bus voltage V_(BUS)) to one or morecontrol modules. Further, the AC/DC power supplies may receive one ormore control signals from the panel control circuit 104 and/or from oneor more input devices for controlling the operation and output voltagesof the AC/DC power supplies (e.g., via internal control circuits of thepower supplies). The AC/DC power supplies may also send command signals(e.g., wired or wireless control signals) to one or more control modulesor electrical loads for controlling operational characteristics (e.g.,pulse-width modulated (PWM) duty cycle, intensity, color, temperature,fade rate, etc.) of the control modules or the electrical loads.Further, the AC/DC power supplies may send feedback signals to the panelcontrol circuit 104 relating to the operation of the power suppliesthemselves, and/or the control modules or the electrical loads.

The power supplies may be rated for any electrical class, for example,Class 1 or Class 2 power supplies. For example, the AC/DC power supply108 may be a Class 2 power supply that receives 100-277 VAC and outputs24V/48V DC. Class 2 power supplies may, for example, be limited to 60VDC and 100 W. The AC/DC converters 110 may be a Low Voltage Class 1power supply (e.g., limited to 15 A, 60V, and 750 W), while the AC/DCconverter 112 may be a High Voltage Class 1 power supply (e.g., limitedto 10 A, 450V, and 4,500 W). The AC/DC converter 110 may receive 100-277VAC, perform power factor correction via a PFC circuit (e.g., a boostconverter or flyback converter), and output 24V/48V DC. The powersupplies of the lighting panel 102 are not limited to Class 1 and Class2 power supplies, but may also be rated as other UL or IECclassifications as required by particular local regulations.Additionally, the lighting panel system 102 may provide power andcontrol signals to motorized shading equipment, such as motorized windowtreatments 160.

The power supplies and/or the panel control circuit 104 of the lightingpanel 102 may be configured to determine the rated class type of a powersupply (e.g., Low Voltage Class 2, Low Voltage Class 1, High VoltageClass 1, etc.). The determination may be made, for example, based on thecontrol modules and/or electrical loads that are connected to the powersupply, and in turn, the desired operational characteristics of thepower supply. For example, the power supply (e.g., or the panel controlcircuit 104) may be configured to measure the amount of current,voltage, and/or power requested on the link, e.g., at the outputterminals of the power supply, to determine its desired class type.Alternatively or additionally, a control module and/or electrical load(e.g., an accessory module located at the electrical load) maycommunicate (e.g., by transmitting a message) to the power supply and/orpanel control circuit 104 indicating its power requirements, such as anamount of power needed, type of dimming required, etc. The power supplymay then be configured (e.g., by the panel control circuit 104) tocontrol (e.g., limit) its output power accordingly (e.g., operate as aLow Voltage Class 2 power supply, a Low Voltage Class 1 power supply, aHigh Voltage Class 1 power supply, etc.). The power supply may also beconfigured to provide an alert and/or report back to the panel controlcircuit 104 upon determining its class type. Further, the panel controlcircuit 104 may be configured to adjust the class type of a power supplyafter installation. For example, a power supply may be initiallyconfigured to operate as a Class 1 power supply (e.g., a High VoltageClass 1 power supply), and later be configured (e.g., by the panelcontrol circuit 104) to operate as another class of power supply (e.g.,as a Low Voltage Class 2 power supply provided that the propercompliance with the relevant standards exists).

Although described with reference to AC/DC power supplies, the lightingpanel 102 may include DC power converters that receive direct DC voltagefrom the DC line feed 134 and output 24V/48V DC, for example. Further,one or more of the power supplies may be configured to receive an ACinput and a DC input, for example, such that the power supply isconfigured to operate in an AC mode when the input voltage is an ACvoltage and in a DC mode when the input voltage is a DC voltage. Anexample of a power supply that is configured to operate in an AC modeand a DC mode is described herein.

The lighting panel 102 may comprise a plurality of control modules forevery power supply (e.g., the AC/DC power supply 108, the AC/DC powerconverter 110, and/or the AC/DC power converter 112). The lighting panel102 may also include physical and/or electrical circuit protection thatmay be located before the power supply, such as breakers 124, and/orafter the control module, such as breakers 126. Additionally, outputbreakers may be configured as electronic breakers whose operatingcharacteristics are adjusted via panel control circuit 104 or a separatecontrol circuit. A plurality of different types of control modules maybe connected to a single power supply, and each control module may beindividually controllable (e.g., by the power supply and/or the panelcontrol circuit 104). Further, the power supply and/or the panel controlcircuit 104 may address each control module uniquely, for example,depending on the functions performed by that control module (e.g., colorchanging, emergency, zoning, etc.). Additionally, the control modulesmay communicate information back to the power supply and/or the panelcontrol circuit 104. For example, the control modules may receiveapproval from the power supply before fully powering on its electricalload (e.g., to prevent overloading the power supply or exceeding theregulatory requirement for the particular class installation).

The lighting panel 102 comprises a plurality of types of control modulesincluding, for example, control modules for driving LED light engines150, control modules for driving a motorized window treatment 160, andcontrol modules for providing digital communication to an electricalload. The control modules may receive DC power from a power supply andprovide controlled power to the electrical load (e.g., power to a LEDlight engine 150, power to a motorized window treatments 160, power toan accessory module remote from the lighting panel 102, and/or thelike). A control module may output the proper power for operation andcontrol of an electrical load, such as the driver module 114, or thecontrol module may operate in tandem with an accessory module located atthe electrical load (e.g., an isolated low voltage converter 116 incombination with an accessory module 152, or a fault detect and branchcircuit 118 in combination with an accessory module 154), such that thetwo in combination provide the proper power for operation and control ofthe electrical load. As such, the lighting panel 102 provides for amodular architecture that allows for select functionality to beperformed within the lighting panel 102 and other functionality to beperformed at the accessory module located at the electrical load.

In additional to modularity, efficiency gains may be realized throughuse of the lighting panel 102. For example, the control module in thelighting panel may output high voltage (e.g., 450V) to an electricalload, which may be more efficient than distribution at lower voltages(e.g., 277V). Further, in instances where the output of the controlmodule in the lighting panel 102 is lower than typical line voltage(e.g., Class 2 scenarios, such as the output of the driver module 114),the power loss at the electrical load may be reduced, the load may runcooler and in turn last longer, and the electrical loads may not requireas much hardware/software located at the load itself, resulting in theload being smaller and more lightweight. If the power supply receives DCinput, the design of the power supply and/or control modules may besimplified (e.g., without PFC-related circuitry), and end-to-endefficiency may be enhanced. Moreover, having a centrally locatedlighting panel 102 within a facility makes maintenance and serviceeasier.

The control modules may output controlled DC power or controlled ACpower, depending on the configuration. The control modules may controlthe output power in accordance with a received command signal from acontrol circuit (e.g., such as the panel control circuit 104), aconnected power supply, a wireless control signal received from an inputdevice, and/or feedback from the electrical load (e.g., temperature,light output, power, color, etc.). The control modules may also providefeedback data to the power supply and/or the panel control circuit 104of the lighting panel 102 (e.g., feedback data relating to theelectrical load, the input power of the control module, intensity levelof a connected light source, load failure conditions, sensor statuses,lumen levels, etc.). A control module may include a dedicated controlcircuit, or may be controlled by the panel control circuit 104 of thelighting panel 102 and/or a control circuit of the associated powersupply.

One example control module is the driver module 114. The driver module114 receives a DC bus voltage V_(BUS) from the AC/DC power supply 108,and provides a regulated DC voltage (e.g., a PWM DC voltage, a constantvoltage DC signal, or a DC level with an imposed communication signaletc.) to the LED light engine 150. For example, the driver module 114may include a load regulation circuit that receives the bus voltageV_(BUS) and controls the amount of power delivered to the LED lightengine 150, for example, to control the intensity of the LED lightengine 150 between a low-end (i.e., minimum) intensity L_(LE) (e.g.,approximately 0.1-5%) and a high-end (i.e., maximum) intensity L_(HE)(e.g., approximately 100%). The driver module 114 may also includeadditional circuitry, such as a current sense circuit and/or a voltagesense circuit. Since the driver module 114 provides a regulated voltageto the LED light engine 150, the LED light engine 150 that is connectedto the driver module 114 may include a minimum amount of hardware and/orsoftware, thereby reducing the cost, size, and complexity of thefixture. For example, the LED light engine 150 may include (e.g., onlyinclude) a single LED or a plurality of LEDs, a resistor, and a lowdrop-out (LDO) regulator that regulates the current through the LEDs.

In other examples, some or all of the functionality of the driver module114 may be split between a control module located in the lighting panel102 (e.g., the isolated low voltage converter 116, the fault detect andbranch circuit 118, or the like) and an accessory module located at theelectrical load (e.g., the accessory modules 152 and 154). As such, thelighting panel 102 provides for a modular design where an electricalload (e.g., LED light engine 150) may include a varying degree ofregulation circuitry, while the remaining portions may reside within acontrol module located within the lighting panel 102 itself.Additionally, and although not illustrated, the lighting panel 102 mayinclude a power supply and the electrical load may include the entiretyof the control module (e.g., within the same housing/fixture). Forexample, the lighting panel may include the AC/DC power supply 108, andthe voltage driver module 114 may be implemented as an accessory modulelocated at the LED light engine 150 (e.g., within the samehousing/fixture).

Further, such modularity of control modules allows for both Class 1 andClass 2 configurations of electrical loads. For example, together, theisolated low voltage converter 116 and the accessory module 152 mayinclude all of the functionality of a LED driver module (e.g., thedriver module 114). The isolated low voltage converter 116 may, forexample, include an isolated converter (e.g., a transformer) and acurrent sense circuit, and the accessory module 152 may include back endregulation at the LED light source 150. As such, the isolated lowvoltage converter 116 may output voltage in accordance with Low VoltageClass 2 requirements. As another example, the fault detect and branchcircuit 118 may include fault detection and regulation circuits, and theaccessory module 154 may include the converter. In such a configuration,the fault detect and branch circuit 118 may output voltage in accordancewith High Voltage Class 1 requirements (e.g., 450V). These are just twonon-limiting examples of how a control module (e.g., the driver module114) may be split between a control module located within the lightingpanel 102 and an accessory module located at the electrical load.

The lighting panel 102 may also include one or more control modules forproviding digital communication to an electrical load (e.g.,communication modules). For example, the lighting panel 102 may includeone or more device control modules 120 and/or accessory communicationmodules 122. The device control module 120 may provide communicationover a dedicated communication line to one or more electrical loads(e.g., motorized window treatments 160) to control operationalcharacteristics of the electrical load (e.g., raise, lower, zoninginformation, unique identifier, etc.). A sensor/keypad module 170 mayreceive wired or wireless digital signals from sensors and/or keypads,and the sensor/keypad module 170 may send digital commands to the devicecontrol module 120 (e.g., via the communication circuit 106) to controlthe electrical loads. The accessory communication module 122 may providecommunication over a dedicated communication line to one or moreelectrical loads (e.g., LED light engines 150) to control operationalcharacteristics of the electrical load (e.g., intensity, color,temperature, fade rate, zoning information, unique identifier, etc.).The accessory communication module 122 may receive digital commands viathe communication circuit 106.

The lighting panel 102 (e.g., the panel control circuit 104, a powersupply, and/or a control module) may provide both data and power to anelectrical load, such as an LED light engine 150 or accessory module152,154, using a single line (e.g., two wires). The electrical load maybe uniquely addressed such that individualized control of and/orcommunication with the electrical load may be performed. For example,the lighting panel 102 may perform a form of power line communication(PLC) when providing DC power to the electrical load, and/or performmodulate a DC voltage to provide communication when powering anelectrical load with DC power. An example form of DC power andcommunication that may be provided over two wires is provided in FIG. 4,which for example, may be used when the power supply is operating as aClass 2 power supply (e.g., AC/DC power supply 108 and the voltagedriver module 114). Alternately, the PLC communication over the DC powerwires may use techniques such as current carrier signals or highfrequency modulated signals to communicate digital information betweenthe lighting loads and the communication circuit 104.

The lighting panel 102 may also include additional control modulesand/or power supplies. For example, the lighting panel 102 may include a0-10V dimming module 142 that provides 0-10V dimming commands to one ormore line voltage electrical loads. The lighting panel 102 may alsoinclude a phase adaptive module 144 used to provide phase controlled ACvoltage to one or more voltage loads (e.g., incandescent lamps orphase-dimmable LED lamps). Further, the lighting panel 102 may include aswitching module 146 that may provide traditional on/off switchingcontrol for one or more electrical loads. Finally, the lighting panel102 may include a shade power supply module 148 that may provide powerand zoning to multiple motorized window treatments 160 (notillustrated).

The panel control circuit 104 may be configured to control the operationof the power supplies and or control modules to selective provide powerdrawn from the AC line feed 132, from the DC line feed 134, and/or fromthe battery bank feed 133. For example, the lighting panel 102 mayinclude a switching circuit configured to switch between directing ACpower or DC power to one or more power supplies, the power suppliesthemselves may receive both AC power and DC power and be configured toswitch between the use of AC power or DC power, or the grid-tie inverter135 may be configured to direct AC power or DC power to one or morepower supplies, for example, based on one or more factors describedherein. For example, in each instance, the control circuit 104 maycontrol the switching between the use of AC power or DC power by the oneor more power supplies. This allows the lighting panel 102 toselectively use power from a particular source based on a variety ofconditions, such as, but not limited to, during AC mains power failure,during times of peak demand reduction, when substantial alternate poweris available from a PV array, etc. Additionally, this selectivedirection of power to the electrical loads may be used to accomplish therequirements of emergency power sourcing to particular lighting loads asrequired by certain national building codes. This system is advantageousin managing the source of emergency power in that is configurable afterthe installation of the system rather than requiring fixture outfittingwith emergency power during the design and installation phase of aproject. In addition to controlling the switch between the use of ACpower or DC power by a power supply, the control circuit 104 may controlone or more characteristics of the electrical loads (e.g., the intensitylevel of an LED light engine 150) based on whether a power supply isreceiving AC power or DC power. For example, the control circuit 104 maylower the intensity (e.g., high-end intensity) of one or more lightingload when using DC power (e.g., only DC power).

The panel control circuit 104 may be configured to control the operationof the power supplies and/or the control modules, for example, inresponse to a user command received via one or more input devices. Forexample, if a power supply and/or control module includes a dedicatedcontrol circuit, then the panel control circuit 104 may manage theoperation of the control circuit of the power supply and/or the controlmodule, and the control circuit of the power supply may control theinternal operation of the power supply and/or associated controlmodule(s) (e.g., and when configured, the control circuit of the controlmodule may control the internal operation of the control module). If,however, the power supply does not include a dedicated control circuit,then the panel control circuit 104 may control the internal operation ofthe power supply and/or associated control module(s). The panel controlcircuit 104 may comprise, for example, a digital controller or any othersuitable processing device, such as, for example, a microcontroller, aprogrammable logic device (PLD), a microprocessor, an applicationspecific integrated circuit (ASIC), or a field-programmable gate array(FPGA).

The panel control circuit 104 may comprise and/or be coupled to memory105. The memory 105 may include one or more components of volatileand/or non-volatile memory, in any combination. The memory 105 may storeoperational characteristics of the components of the lighting panel 102.The lighting panel power supply 107 may generate a direct-current (DC)supply voltage V_(CC) for powering the panel control circuit 104 and theother low-voltage circuitry of the lighting panel 102. The lightingpanel power supply 107 may be coupled to the AC line feed 132, the DCline feed 134, the battery bank feed 133, and/or a power supply (e.g.,AC/DC power supply 108, 110, 112) via the electrical connections 109.The panel control circuit 104 may be connected to and configured tocontrol any combination of components (e.g., all components) of thelighting panel 102.

The communication circuit 106 of the lighting panel 102 may be coupledto a gateway device 138 and/or one or more data terminals 136, which forexample, may include a network link (e.g., Ethernet port), a digitalcommunication link, a Digital Multiplex (DMX) link, etc. Thecommunication circuit 106 may be configured to communicate via awireless communication link, such as a radio-frequency (RF)communication link or an infrared (IR) communication link.

The load control system 100 may comprise one or more input devices, suchthat the lighting panel 102 is configured to receive user inputs,transmit digital messages, and/or receive digital messages via the inputdevices. The digital messages may be transmitted via wired (e.g.,through a wired communication link) or wireless signals (e.g., the RFsignals). For example, the input devices may include one or more of anaccess point or hub 166, a wireless sensor 162 (e.g., anoccupancy/vacancy sensor, a daylight sensor, etc.), a wireless keypad164 (e.g., a battery-powered handheld remote control device), asensor/keypad module 170, a wired sensor 172 (e.g., an occupancy/vacancysensor, a daylight sensor, etc.), a visual display remote control device174 (e.g., a dynamic keypad), a wireless mobile device 180, a webinterface 182, a wall-mounted remote control device (not shown), etc.The access point or hub 166 may be configured to transmit and receivewired and wireless signals, and may include a network connection to thelighting panel 102 (e.g., the panel control circuit 104 and/or thecommunication circuit 106) and may act as a standard protocol (e.g.,Wi-Fi) access point and/or a proprietary protocol (e.g., theClearConnect® protocol) access point for one or more input devicesand/or electrical loads. The sensor/keypad module 170 may include a QSlink to one or more wire devices, such as the wired sensor 172 and thevisual display remote control device 174, and may be configured tocommunicate wirelessly using a proprietary protocol (e.g., theClearConnect® protocol).

The digital messages may include information such as a command, a query,and/or identifying information. For example, the digital messagestransmitted by the input device may include a unique identifier (e.g., aserial number) associated with the transmitting input device. Thewireless signals carrying the digital messages may be transmitted at acertain communication frequency or frequency range f_(RF) (e.g.,approximately 434 MHz, 900 MHz, 2.4 GHz, or 5.6 GHz). The transmissionmay utilize a proprietary communication protocol, such as theClearConnect® protocol, Wi-Fi, Bluetooth®, ZIGBEE, Z-WAVE, KNX-RF,ENOCEAN RADIO, and/or a different proprietary protocol.

The input devices may be assigned to one or more components of the loadcontrol system 100 (e.g., the lighting panel 102, the panel controlcircuit 104, a power supply (e.g., AC/DC power supply 108, an AC/DCpower converter 110, and/or an AC/DC power converter 112), a controlmodule (e.g., control module 114, 116, or 118, communication module 120or 122), an accessory module (e.g., the accessory module 152 or 154),and/or a motorized window treatment 160) during a configurationprocedure of the load control system 100, such that the load controlsystem, e.g., the lighting panel 102, may be responsive to digitalmessages transmitted by the input devices. Examples of methods ofassociating control devices are described in greater detail incommonly-assigned U.S. Patent Application Publication No. 2008/0111491,published May 15, 2008, entitled RADIO-FREQUENCY LIGHTING CONTROLSYSTEM; U.S. Patent Application Publication No. 2013/0214609, publishedAug. 22, 2013, entitled TWO-PART LOAD CONTROL SYSTEM MOUNTABLE TO ASINGLE ELECTRICAL WALLBOX; and U.S. patent application Ser. No.13/830,237, filed Mar. 14, 2013, entitled COMMISSIONING LOAD CONTROLSYSTEMS; the entire disclosures of which are hereby incorporated byreference.

The communication circuit 106 of the lighting panel 102 may be connectedto the gateway device 138 (e.g., a bridge) and may be configured toenable communication with a network, such as a wireless network and/orwired local area network (LAN). The gateway device 138 may be connectedto a router (not shown) via a wired digital communication link (e.g., anEthernet communication link). The router may allow for communicationwith the network, e.g., for access to the Internet. The gateway device138 may be wirelessly connected to the network, e.g., using Wi-Fitechnology. The gateway device 138 may be configured to transmit the RFsignals to one or more components of the lighting panel 102 and/or anaccessory module for controlling the respective electrical loads inresponse to digital messages received from external devices via thenetwork. The transmission may use a proprietary protocol describedherein. The gateway device 138 may be configured to receive digitalmessages from the accessory modules of the load control system 100(e.g., via the RF signals and/or using a proprietary protocol). Thegateway device 138 may be configured to transmit digital messages viathe network for providing data (e.g., status information) to externaldevices. The gateway device 138 may operate as a central controller forthe lighting panel 102, or may relay digital messages between theaccessory modules of the load control system 100 and the network. Forexample, feedback and/or reports may be received (e.g., by the panelcontrol circuit 104) from the accessory modules of the load controlsystem 100 and sent over the network (e.g., via the gateway device 138)to a user.

The lighting panel 102 may be in communication with a systemadministration (e.g., a system administrator server) via the gatewaydevice 138. For example, the panel control circuit 104 may be configuredto provide a report relating to the operation and/or configuration ofthe lighting panel 102 and/or other components of the lighting controlsystem 100 to the system administrator. Further, the systemadministrator may be able to configure one or more components of thelighting panel 102 and/or other components of the lighting controlsystem 100 from a remote location. A report may include one or morenotification, alerts, or summaries relating to a failed component, areconfigured component (e.g., change of rated class of a power supply),an additional load being connected to the lighting panel 102, operationof the grid-tie inverter, a switch between AC-DC or vice versa, digitalmessages sent/received within the lighting system 100, demands of thelighting system 100, commissioning of components of the lighting system100, etc.

The wireless mobile device 180 (e.g., a network device) may include asmart phone (e.g., an iPhone® smart phone, an Android® smart phone, or aBlackberry® smart phone), a personal computer, a laptop, awireless-capable media device (e.g., MP3 player, gaming device, ortelevision), a tablet device (e.g., an iPad® hand-held computingdevice), a Wi-Fi or wireless-communication-capable television, or anyother suitable Internet-Protocol-enabled device. For example, thewireless mobile device 180 may be configured to transmit RF signals tothe gateway device 138 via a Wi-Fi communication link, a Wi-MAXcommunications link, a Bluetooth® communications link, a near fieldcommunication (NFC) link, a cellular communications link, a televisionwhite space (TVWS) communication link, or any combination thereof.Examples of lighting systems operable to communicate with wirelessmobile devices 180 on a network are described in greater detail incommonly-assigned U.S. Patent Application Publication No. 2013/0030589,published Jan. 31, 2013, entitled LOAD CONTROL DEVICE HAVING INTERNETCONNECTIVITY, the entire disclosure of which is hereby incorporated byreference.

The lighting panel 102 may also include a combination grid-tieinverter/battery charger 135. Alternatively, the lighting panel 102 maynot include the grid-tie inverter/battery charger 135 (e.g., the loadcontrol system may include a grid-tie inverter external to the lightingpanel), and may include a single DC line feed (e.g., the DC line feed134). With either configuration, a connection may be provided for tyingthe lighting panel 102 back to the AC power grid so that the lightingpanel 102 may feed excess power back to the grid (e.g., via the AC linefeed 132). For example, the lighting panel 102 may use a portion of theDC power that is received from the DC power source (e.g., via the DCline feed 134 and/or via the battery bank feed 133) for powering one ormore electrical loads, and sell any remaining DC power back to the gridvia the grid-tie inverter 135. The panel control circuit 104 maydetermine how much DC power to use versus to sell back to the grid basedon one or more factors (e.g., environmental conditions, price index ofthe AC power, time of day, etc.). Further, the panel control circuit 104may decide to lower the power provided to one or more electrical loads(e.g., dim one or more LED light engines 150) based on the amount ofreceived DC power, potentially within a window of acceptance and/orbased on one or more of the factors, such that the lighting panel 102limits the amount of received AC power (e.g., potentially doesn'treceive any AC power).

The lighting panel 102 may be connected to an AC power supply via the ACline feed 132, to a DC power supply via the DC line feed 134, and to abattery bank via the battery bank feed 133. The grid-tieinverter/battery charger 135 of the lighting panel 102 may be connectedto a battery bank via the battery bank feed 133 and/or to a DC powersource (e.g., an alternative energy source, such as a PV power supply)via the DC line feed 134. The lighting panel 102 may provide power toany one or more of the electrical loads during any emergency situation(e.g., to power one or more LED light engines 150) using energy storedin the battery bank. Therefore, the panel control circuit 104 mayconfigure any of the connected electrical loads to operate as anemergency device (e.g., emergency lighting) during an emergencysituation, for example, after installation and without having to connectdedicated batteries to a specific electrical load or to each electricalload. Further, the panel control circuit 104 may be configured torecharge the battery bank via the grid-tie inverter/battery charger 135using the DC power source and/or the AC power source, for example, suchthat the battery bank does not need replenishment. Alternatively oradditionally, the lighting panel 102 may use DC power received from theDC power supply and/or the battery bank directly to power the electricalloads in emergency situations, for example, with the use of the batterybank or a site based generation facility.

The load control system 100 may be configured (e.g., programmed) througha commissioning procedure. For example, the devices of the load controlsystem 100 (e.g., the control modules of the lighting panel 102, theaccessory modules 152, 154, the input devices, etc.) may be associatedwith one another, for example, through a commissioning procedure. Acombination of communication features may be used to create an intuitiveand simple way to accomplish the commissioning aspects of an addressablelighting system. The mobile device 180 may be used to commission theload control system 100. For example, the load control system 100 mayinclude a plurality of lighting fixtures (e.g., the LED light engines150 having accessory modules 152, 154), where each of the lightingfixtures are individually addressable, and as such, the load controlsystem 100 may be installed and configured to the particular applicationwith little regard (e.g., restriction) to the actual wiring structureutilized. The mobile device 180 may be used to perform zoning offixtures after installation and without having to rewire the loadcontrol system 100. For example, the lighting panel 102 may beconfigured to control (e.g., simultaneously control) a plurality oflighting fixtures that abut a row of windows in a building together toaccomplish a daylight harvesting function, even though the lightingfixtures are not wired together. For instance, the lighting panel 102may store and utilize a unique address to control the behavior of eachlighting fixture. Further, the lighting panel 102 may store a databaserelating the particular behavior of each of the electrical loads in aspace for a variety of control inputs. The lighting panel 102 may usethe database to determine the relationships and commands for each powersupply and control module (e.g., for zoning, daylight harvesting, etc.),and the lighting panel 102 may create the database during thecommissioning process.

The lighting panel 102 may perform commissioning in such a manner as toreduce the time and labor typically required to associate multipleelectrical loads with one or more controls. For example, the electricalloads (e.g., the LED light fixtures 150) may include a radio beacon (notshown), such as a Bluetooth beacon. Each radio beacon may include aradio transmitter and ultimately provides addressability for anelectrical load. In addition, the accessory modules 152, 154 may beconfigured to transmit a beacon signal. The radio beacon in theelectrical load may broadcast a unique identifier of the radio beacon(e.g., serial number) via radio signals that may be received by themobile device 180. The electrical loads may include a wired or wirelessconnection back to the lighting panel 102, for example, to a controlmodule (e.g., the driver module 114), communication module 122, and/orcommunication circuit 106. The lighting panel 102 may create a databaserelating to how to group electrical loads based on the received signalstrength of the broadcast signal (e.g., and in turn, the proximity ofthe radio beacon to the mobile device 180). The database may be createdduring the commissioning process and used to determine the behavior fora plurality of loads in a particular space. To create the database, themobile device 180 may receive and determine a signal strength and uniqueidentifier of a radio beacon. Using the receiving signal strength, themobile device 180 may group or associated one or more electrical loadstogether for commissioning purposes in the database. After theassociation of electrical load and radio beacon is established andstored in the database of the lighting panel 102, the lighting panel 102may control a group of electrical loads together based on theidentification information of each electrical load and/or associatedcontrol function, for example, via a wireless or a wired communicationchannel between lighting panel 102 and the electrical load. Examples ofsystems that perform commissioning and example commissioning proceduresare described in greater detail in commonly-assigned U.S. ProvisionalPatent Application No. 62/279,409, filed Jan. 15, 2016, and U.S.Provisional Patent Application No. 62/326,466, filed Apr. 22, 2016, bothentitled COMMISSIONING LOAD CONTROL SYSTEMS, the entire disclosures ofwhich are hereby incorporated by reference.

The lighting panel 102 may include additional power supplies (e.g., N+1power supplies) of a particular type, such as the AC/DC power supplies108, the AC/DC power converters 110, and/or the AC/DC power converters112. Further, the lighting panel 102 may include additional controlmodules (e.g., N+1 control modules) of a particular type, such as thedriver modules 114, the isolated low voltage converters 116, or thefault detect and branch circuits 118. In such instances, the panelcontrol circuit 104 of the lighting panel 102 may be configured toswitch-in (e.g., automatically switch-in) a power supply or controlmodule if a power supply or control module were to fail. For example,the panel control circuit 104 may be configured to detect that a powersupply or control module has failed or was in danger of failing, andupon such a determination, the panel control circuit 104 may reroute thecircuit through an additional power supply or control module so thefailure does not cause an interruption of power (e.g., an extendeddisruption of power) to the electrical load. As such, the electricalload(s) receiving power from the failed power supply or control modulewould not lose power for an extended period or not lose power at all,depending on the detection time and/or the switch-in time for theadditional power supply or control module. Further, the panel controlcircuit 104 may be configured to provide a notification, for example, toa system administrator, if a power supply or control module were tofail. Accordingly, the system administrator may replace the failed powersupply or control module within the lighting panel 102 without having totake any electrical loads offline.

FIG. 2 is a simplified block diagram of a system 200 including anexample power supply 208 and an example control module 214 of the loadcontrol system of FIG. 1. The power supply 208 is an example of thepower supply 108, and the control module 214 is an example of the drivermodule 114. Also illustrated in the system 200 is the panel controlcircuit 104 of the lighting panel 102 and power supply 107 of thelighting panel 102, but the specific configuration of these componentswith respect to the power supply 208 and control module 214 is anexample configuration. Further, it should be noted that the power supply208 may also include memory and a communication circuit, and/or thepower supply 208 may include a dedicated internal power supply insteadof using the power supply of the lighting panel 107.

The power supply 208 and the control module 214 may be configured tocontrol the amount of power delivered to an electrical load, such as,the LED light engine 150, and thus the intensity of the electrical load.The LED light engine 150 is shown as a plurality of LEDs connected inseries but may comprise a single LED or a plurality of LEDs connected inparallel or a suitable combination thereof, depending on the particularlighting system. The power supply 208 may comprise a first inputterminal 212 (e.g., a hot terminal) and a second input terminal 216(e.g., a neutral terminal) that are adapted to be coupled to a powersource (not shown), e.g., via the AC line feed 132, the DC line feed134, and/or the battery bank feed 133. The first and second inputterminals 212, 216 may be configured to receive an input voltage V_(IN),e.g., an AC mains input voltage or a DC input voltage. The power supply208 also includes a power supply control circuit 244, however in someexamples, the power supply control circuit 244 may be omitted and, forexample, the power supply 208 may be controlled entirely by the panelcontrol circuit 104 of the lighting panel 102.

The power supply 208 may comprise a radio-frequency (RFI) filter circuit204, a rectifier circuit 206, a boost converter 202, and/or a rippledetect circuit 218. The RFI filter circuit 204 may minimize the noiseprovided on the AC mains. The rectifier circuit 204 may be a dynamicrectifier circuit configured to change its operation in response towhether an AC voltage or a DC voltage is present at the input terminals212, 216. The rectifier circuit 206 may be configured to rectify theinput voltage V_(IN) to generate a rectified voltage V_(RECT) when theinput terminals are connected to an AC power source and an AC voltage ispresent at the input terminals 212, 216. The rectifier circuit 206 maybe configured to pass through the input voltage V_(IN) (e.g., notrectify the input voltage V_(IN)) when the input terminals are connectedto a DC power source and a DC voltage is present at the input terminals212, 216 of the power supply 208.

The boost converter 202 may receive the rectified voltage V_(RECT) andgenerate a boosted DC bus voltage V_(BUS) across a bus capacitor C_(BUS)(e.g., an electrolytic capacitor). The boost converter 202 may compriseany suitable power converter circuit for generating an appropriate busvoltage, such as, for example, a flyback converter, a single-endedprimary-inductor converter (SEPIC), a Ćuk converter, or other suitablepower converter circuit. The boost converter 202 may operate as a PFCcircuit to adjust the power factor of the power supply 208 towards apower factor of one. The power supply 208 may comprise an inputcapacitor C_(IN) (e.g., a film capacitor) coupled across the input ofthe boost converter 202. Examples of boost converters are described ingreater detail in commonly-assigned U.S. Pat. No. 8,492,987, issued Jul.23, 2013, and U.S. Pat. No. 8,680,787, issued Mar. 25, 2014, bothentitled LOAD CONTROL DEVICE FOR A LIGHT-EMITTING DIODE LIGHT SOURCE,the entire disclosures of which are hereby incorporated by reference.

The control module 214 may comprise a load regulation circuit 230 and/ora current sense circuit 240. The load regulation circuit 230 may receivethe bus voltage V_(BUS) and control the amount of power delivered to theLED light engine 150, for example, to control the intensity of the LEDlight engine 150. An example of the load regulation circuit 230 may bean isolated, half-bridge forward converter. An example of a forwardconverter is described in greater detail in commonly-assigned U.S. Pat.No. 9,253,829, issued Feb. 2, 2015, entitled LOAD CONTROL DEVICE FOR ALIGHT-EMITTING DIODE LIGHT SOURCE, the entire disclosure of which ishereby incorporated by reference. The load regulation circuit 230 maycomprise, for example, a buck converter, a linear regulator, or anysuitable LED drive circuit for adjusting the intensity of the LED lightengine 150.

The power supply control circuit 244 may be configured to control theoperation of the boost converter 202 of the power supply 208. Forexample, the power supply control circuit 244 may generate a bus voltagecontrol signal V_(BUS-CNTL), which may be provided to the boostconverter 202 for adjusting the magnitude of the bus voltage V_(BUS)towards a target bus voltage V_(BUS-TARGET). The power supply controlcircuit 244 may receive a bus voltage feedback control signal V_(BUS-FB)from the boost converter 202, which may indicate the magnitude of thebus voltage V_(BUS).

The control module 214 may comprise a module control circuit 254, whichmay generate drive control signals V_(DR1), V_(DR2). The drive controlsignals V_(DR1), V_(DR2) may be provided to the load regulation circuit230 of the control module 214 for adjusting the magnitude of a loadvoltage V_(LOAD) generated across the LED light engine 150 and themagnitude of a load current I_(LOAD) conducted through the LED lightengine 150, for example, to control the intensity of the LED lightengine 150 to a target intensity L_(TRGT). The module control circuit254 may adjust an operating frequency fop and/or a duty cycle D_(CINV)(e.g., an on time T_(ON)) of the drive control signals V_(DR1), V_(DR2)to adjust the magnitude of the load voltage V_(LOAD) and/or the loadcurrent I_(LOAD). The module control circuit 254 may receive a loadvoltage feedback signal V_(V-LOAD) generated by the load regulationcircuit 230. The load voltage feedback signal V_(V-LOAD) may indicatethe magnitude of the load voltage V_(LOAD). The power supply controlcircuit 244 of the power supply 208 may operate independently of themodule control circuit 254 of the control module 214. In addition, thepower supply control circuit 244 may be configured to communicate withthe module control circuit 254 to allow the power supply control circuit244 and the module control circuit 254 to work together to control theoperation of the system 200.

The current sense circuit 240 of the control module 214 may receive asense voltage V_(SENSE) generated by the load regulation circuit 230.The sense voltage V_(SENSE) may indicate the magnitude of the loadcurrent I_(LOAD). The current sense circuit 240 may receive asignal-chopper control signal V_(CHOP) from the module control circuit254. The current sense circuit 240 may generate a load current feedbacksignal VT-LOAD, which may be a DC voltage indicating the averagemagnitude I_(AVE) of the load current I_(LOAD). The module controlcircuit 254 may receive the load current feedback signal VT-LOAD fromthe current sense circuit 240 and control the drive control signalsV_(DR1), V_(DR2) accordingly. For example, the module control circuit254 may control the drive control signals V_(DR1), V_(DR2) to adjust amagnitude of the load current I_(LOAD) to a target load current I_(TRGT)to thus control the intensity of the LED light engine 150 to the targetintensity L_(TRGT) (e.g., using a control loop). The module controlcircuit 254 may be configured to determine a load power P_(LOAD)presently being consumed by the LED light engine 150 using the loadvoltage feedback signal V_(V-LOAD) and the load current feedback signalV_(I-LOAD). The load current I_(LOAD) may be the current that isconducted through the LED light engine 150. The target load currentI_(TRGT) may be the current that the module control circuit 254 wouldideally like to conduct through the LED light engine 150 (e.g., based atleast on the load current feedback signal V_(I-LOAD)).

The power supply 208 may also comprise a ripple detect circuit 218,which may receive the rectified voltage V_(RECT) and may generate aripple detect signal V_(RIP-DET) that may indicate whether AC ripple ispresent or not on the rectified voltage V_(RECT) (e.g., whether an ACvoltage or a DC voltage, respectively is coupled to the input terminals212, 216). The power supply control circuit 244 may receive the rippledetect signal V_(RIP-DET) and may operate in an AC mode if an AC voltageis coupled to the input terminals 212, 216 or a DC mode if a DC voltageis coupled to the input terminals 212, 216. The ripple detect circuit218 may also be coupled to receive the input voltage V_(IN) and/or thebus voltage V_(BUS).

The power supply 208 may also comprise a controllable switching circuit218 (e.g., including a MOSFET) electrically coupled in series with thebus capacitor C_(BUS) for disconnecting the bus capacitor. Whenoperating in the AC mode, the power supply control circuit 244 mayenable the operation of the boost converter 202 of the power supply 208to generate the bus voltage V_(BUS) across the bus capacitor C_(BUS).The power supply control circuit 244 may render the controllableswitching circuit 218 conductive and may control the magnitude of thebus voltage V_(BUS) to a maximum magnitude V_(BUS-MAX) (e.g.,approximately 465 volts). The power supply control circuit 244 may alsooperate the boost converter 202 as a PFC circuit during the AC mode toadjust the power factor of the power supply 208 towards a power factorof one.

When operating in the DC mode, the power supply control circuit 244 maybe configured to disable the operation of the boost converter 202 toreduce the power loss in the power supply 208 due to the power loss inthe boost converter when enabled. When disabled, the boost converter 202may pass through the DC voltage from the input terminals 212, 216 andthe bus voltage V_(BUS) may have a minimum magnitude V_(BUS-MIN) (e.g.,approximately 380 volts). When operating in the DC mode, the powersupply control circuit 244 may be configured to enable the boostconverter 202 during a startup routine of the power supply 208 anddisable the boost converter 202 during normal operation. Further, thepower supply control circuit 244 may render the controllable switchingcircuit 218 conductive to disconnect the bus capacitor C_(BUS) in the DCmode since the bus capacitor may not be required when the DC voltage ispresent at the input terminals. Rather than disabling the boostconverter 202 in the DC mode, the power supply control circuit 244 mayalso scale back the operation of the boost converter (e.g., reduce thetarget bus voltage V_(BUS-TARGET)) in order to reduce the losses in theboost converter 202.

The control module 214 may also comprise a capacitor C_(FILM) (e.g., afilm capacitor) coupled across the input of the load regulation circuit230 for supplying high-frequency current that may be required tocirculate through the load regulation circuit. Since the bus capacitorC_(BUS) may comprise one or more electrolytic capacitors, disconnectingthe bus capacitor C_(BUS) of the power supply 208 may increase thelifetime of the LED driver 100. In addition, disconnecting the buscapacitor C_(BUS) may reduce an inrush current conducted by the powersupply 208 when power is applied to the input terminals 212, 216.

The power supply control circuit 244 may also enable the operation ofthe boost converter 202 in the DC mode when the power P_(LOAD) requiredby LED light engine 150 exceeds a threshold amount P_(TH) (e.g.,approximately 80%). In addition, the power supply control circuit 244may also be configured to control the target bus voltage V_(BUS-TARGET)as a function of the power P_(LOAD) required by LED light engine 150(e.g., if the power supply control circuit 244 is configured tocommunicate with the module control circuit 245 to determine the powerP_(LOAD) required by LED light engine 150). The power supply controlcircuit 244 may be configured to adjust the target bus voltageV_(BUS-TARGET) linearly between the minimum magnitude V_(BUS-MIN) andthe maximum magnitude V_(BUS-MAX) when the power P_(LOAD) required byLED light engine 150 is above the threshold amount P_(TH). The powersupply control circuit 244 may be configured to control the target busvoltage V_(BUS-TARGET) using open loop control, for example, by using alookup table to determine the target bus voltage V_(BUS-TARGET) inresponse to the target intensity L_(TRGT) and/or target load currentI_(TRGT). The power supply control circuit 244 may also be configured tocontrol the target bus voltage V_(BUS-TARGET) using closed loop control,for example, by using the load voltage feedback signal V_(V-LOAD) andthe load current feedback signal V_(I-LOAD) to determine the powerP_(LOAD) required by LED light engine 150. The power supply controlcircuit 244 could also be configured to learn the target intensityL_(TRGT) and/or target load current I_(TRGT) at which the power P_(LOAD)required by LED light engine 150 exceeds the threshold amount P_(TH)(e.g., during a startup routine).

FIG. 3 is a simplified block diagram of an example load regulationcircuit (e.g., a forward converter) and current sense circuit of anexample control module 314. The control module 314 may include a forwardconverter 330 and/or a current sense circuit 340. The control module 314may be an example of the control module 214, the forward converter 330may be an example of the load regulation circuit 230 of the controlmodule 214, and the current sense circuit 340 may be an example of thecurrent sense circuit 240 of the control module 214.

The forward converter 330 may comprise a half-bridge inverter circuithaving two field effect transistors (FETs) Q310, Q312 for generating ahigh-frequency inverter voltage V_(INV) from the bus voltage V_(BUS).The FETs Q310, Q312 may be rendered conductive and non-conductive inresponse to the drive control signals V_(DR1), V_(DR2). The drivecontrol signals V_(DR1), V_(DR2) may be received from the module controlcircuit 254. The drive control signals V_(DR1), V_(DR2) may be coupledto the gates of the respective FETs Q310, Q312 via a gate drive circuit318 (e.g., which may comprise part number L6382DTR, manufactured by STMicroelectronics). The module control circuit 254 may generate theinverter voltage V_(INV) at a constant operating frequency fop (e.g.,approximately 60-65 kHz) and thus a constant operating period T_(OP).However, the operating frequency fop may be adjusted under certainoperating conditions. For example, the operating frequency fop may bedecreased near the high-end intensity L_(HE). The module control circuit254 may be configured to adjust a duty cycle DC_(INV) of the invertervoltage V_(INV) to control the intensity of an LED light engine 150towards the target intensity L_(TRGT). The module control circuit 254may adjust the duty cycle DC_(INV) of the inverter voltage V_(INV) toadjust the magnitude (e.g., the average magnitude I_(AVE)) of the loadcurrent I_(LOAD) towards the target load current I_(TRGT). The magnitudeof the load current I_(LOAD) may vary between a maximum rated currentI_(MAX) and a minimum rated current I_(MIN).

The inverter voltage V_(INV) is coupled to the primary winding of atransformer 320 through a DC-blocking capacitor C316 (e.g., which mayhave a capacitance of approximately 0.047 g), such that a primaryvoltage V_(PRI) is generated across the primary winding. The transformer320 may be characterized by a turns ratio n_(TURNS) (i.e., N₁/N₂), whichmay be approximately 115:29. A sense voltage V_(SENSE) may be generatedacross a sense resistor R322, which may be coupled in series with theprimary winding of the transformer 320. The FETs Q310, Q312 and theprimary winding of the transformer 320 may be characterized by parasiticcapacitances C_(P1), C_(P2), C_(P3), respectively. The secondary windingof the transformer 320 may generate a secondary voltage. The secondaryvoltage may be coupled to the AC terminals of a full-wave dioderectifier bridge 324 for rectifying the secondary voltage generatedacross the secondary winding. The positive DC terminal of the rectifierbridge 324 may be coupled to the LED light engine 150 through an outputenergy-storage inductor L326 (e.g., which may have an inductance ofapproximately 10 mH), such that the load voltage V_(LOAD) may begenerated across an output capacitor C328 (e.g., which may have acapacitance of approximately 3 μF).

The current sense circuit 340 may comprise an averaging circuit forproducing the load current feedback signal V_(I-LOAD). The averagingcircuit may comprise a low-pass filter comprising a capacitor C342(e.g., which may have a capacitance of approximately 0.066 uF) and aresistor R332 (e.g., which may have a resistance of approximately 3.32kΩ). The low-pass filter may receive the sense voltage V_(SENSE) via aresistor R334 (e.g., which may have a resistance of approximately 1 kΩ).The current sense circuit 340 may comprise a transistor Q336 coupledbetween the junction of the resistors R332, R334 and circuit common. Thegate of the transistor Q336 may be coupled to circuit common through aresistor R338 (e.g., which may have a resistance of approximately 22kΩ). The gate of the transistor Q336 may receive the signal-choppercontrol signal V_(CHOP) from the module control circuit 254. An exampleof the current sense circuit 340 may be described in greater detail incommonly-assigned U.S. patent application Ser. No. 13/834,153, filedMar. 15, 2013, entitled FORWARD CONVERTER HAVING A PRIMARY-SIDE CURRENTSENSE CIRCUIT, the entire disclosure of which is hereby incorporated byreference.

FIG. 4 is an example of a timing diagram of a DC voltage V_(DC)generated by a control module of a lighting panel (e.g., the lightingpanel 102) for provide power and communicating digital messages to anelectrical load. The timing diagram 400 illustrates an example datapattern of a transmitted digital message carried via the DC voltageV_(DC). The DC voltage V_(DC) and the data pattern may be generated by acontrol module (e.g., the driver module 114) of the lighting panel 102.For example, the driver module 114 may be configured to pulse-widthmodulate (PWM) the DC voltage V_(DC) to introduce a reference edge and adata edge into the DC voltage V_(DC). The time period between successivereference edges may be consistent and may define a communication timeperiod. The communication time period may be static or adjustable basedon the electrical load. Digital information (e.g., bits of thetransmitted digital messages) may be encoded in the PWM duty cycle ofthe DC voltage V_(DC). For example, the bits of the transmitted digitalmessages may be encoded in the firing time of a data edge (e.g., a dataedge time) of the driver module 114 as measured with respect to a firingtime of a reference edge (e.g., a reference edge time). In other words,the bits of the transmitted digital messages may be encoded as afunction of the firing times of the reference and data edges.

The value of the digital data transmitted by the control module may bedependent upon an offset time period T_(OS) (i.e., a difference) betweenthe data edge and the previous reference edge. The control module maycontrol the data edges to be at one of four times across the time windowT_(WIN), thus resulting in one of four offset time periods T_(OS1),T_(OS2), T_(OS3), T_(OS4), from the previous reference edge, such thattwo bits may be transmitted each communication time period. To transmitbits “00”, the control module may be configured operable to pulse widthmodulate the DC voltage V_(DC) at the first possible data edge time,such that the first offset time period Tosi exists between the referenceedge and the data edge. For example, each of the possible data edgetimes may be an offset period difference ΔT_(OS) apart. The controlmodule may be configured to control the offset time period T_(OS)between the reference edge and the data edge to the second offset timeperiod T_(OS2) to transmit bits “01”, to the third offset time periodT_(OS3) to transmit bits “10”, and the fourth offset time period T_(OS4)to transmit bits “11”, for example, as shown in FIG. 4.

To decode the data, a control circuit (e.g., microprocessor) of eachelectrical load (e.g., LED light engine 150, accessory module, etc.) maydetermine if the offset time period T_(OS) of each data pattern isapproximately equal to one of the four offset time periods T_(OS1),T_(OS2), T_(OS3), T_(OS4) within a default tolerance ΔT_(OS), which maybe equal to, for example, approximately fifty microseconds.Alternatively, the number of data edges possible in the time windowT_(WIN) could be greater than four (e.g., eight) in order to transmitmore than two bits of data during each communication time period. Thecontrol modules of the lighting panel 102 may be configured to set thecommunication time period and number of data edges possible in each timewindow T_(WIN) such that, for example, the electrical load is operableacross its entire range when receiving just a portion of the full DCvoltage V_(DC) (e.g., the communication time period minus the entiretime window).

When the control module is not transmitting a digital message to theelectrical load, the control module may provide a fully conductive DCvoltage V_(DC). Accordingly, the DC voltage V_(DC) would not have atleast one reference edge in each communication cycle when the controlmodule is not transmitting a digital message to the electrical load.Alternatively, the control module may pulse width modulate the DCvoltage V_(DC) at the first data edge (e.g., at T_(OS1)), as if thecontrol module was continuously transmitting bits “00.” Further, anaccessory module may be configured to respond to the control module in asimilar fashion. For example, a response time window T_(RWIN) may beused where, for example, the offset time period T_(OS) between areference edge and a data edge in the response time window T_(RWIN) isused to determine the response communication performed by the accessorymodule. The response time window T_(RWIN) may be smaller in durationthan the time window T_(WIN), for example, since less information mayneed to be transmitted from the accessory module to the control modulein the lighting panel 102. Alternatively, every other time windowT_(WIN) may be used as the response time window T_(RWIN).

The system utilizing the methods shown in FIG. 4 allows for reuse ofexisting building wiring to accommodate new lighting fixtures as onlytwo wires are required between the lighting panel and lighting fixtures.For example, this legacy configuration of wiring may exist betweentraditional dimming panels and the traditional lighting loads, such asincandescent bulbs. As no new wires are required between the lightingpanel location and the fixture location, this new system provides anopportunity for system upgrades without pulling new wires.

FIG. 5 is an example flowchart of a power supply classificationdetection procedure 500 performed by an electrical panel, such as thelighting panel 102. The electrical panel may detect (e.g., automaticallydetect) the rated class type of one or more power supplies of theelectrical panel. For example, the rated class types may include, butare not limited to, Low Voltage Class 2, Low Voltage Class 1, and HighVoltage Class 1. Although the detection procedure 500 is described withreference to the Low Voltage Class 2, the Low Voltage Class 1, and theHigh Voltage Class 1 class types, the detection procedure 500 may detectany combination or type of rated class types of power supplies. Further,it should be appreciated that a panel control circuit (e.g., the panelcontrol circuit 104) and/or one or more of the power supplies themselvesmay perform the detection procedure 500.

The electrical panel may set N=0 at 510, where N_(MAX) is the totalnumber of power supplies of the electrical panel (e.g., the total numberof adjustable/configurable power supplies of the electrical panel). At520, the electrical panel may determine the rated class of the powersupply N. The electrical panel may determine the rated class of thepower supply, for example, based on the control modules and/orelectrical loads that are connected to the power supply, and in turn,the desired operational characteristics of the power supply. Forexample, the power supply and/or the panel control circuit may beconfigured to measure the amount of current, voltage, and/or powerrequested on the link, e.g., at the output terminals of the powersupply, to determine its desired class type. Alternatively oradditionally, a control module and/or electrical load (e.g., anaccessory module located at the electrical load) may communicate (e.g.,by transmitting a digital or analog message) to the power supply and/orpanel control circuit indicating its power requirements, such as anamount of power needed, type of dimming required, etc.

After determining the rated class of the power supply N at 520, theelectrical panel may configured the power supply N to operate accordingto the rated class at 530. For example, the electrical panel mayconfigure the power supply to control (e.g., limit) its output poweraccordingly (e.g., operate as a Low Voltage Class 2 power supply, a LowVoltage Class 1 power supply, a High Voltage Class 1 power supply,etc.). At 540, the electrical panel may send a notification (e.g., analert and/or report) of the rated class type of the power supply N. Forexample, the panel control circuit may send a notification of the ratedclass type of the power supply N to a network or system administration(e.g., via the gateway device 138). Further, in instances where thedetection procedure 500 is performed by the power supplies themselves,the power supply N may send a notification to the panel control circuitat 540 indicating its rated class type. Further, in instances where thedetection procedure 500 is performed by the power supplies themselves,510, 550, and 560 of the detection procedure 500 may be omitted.

At 550, the electrical panel may determine whether the N=N_(MAX). If theelectrical panel determines that N is less than N_(MAX), then theelectrical panel may increment N by 1 at 560, and repeat 520-540 for asubsequent power supply. If the electrical panel determines thatN=N_(MAX) at 550, then the detection procedure 500 may exit. Theelectrical panel may perform the detection procedure 500 at start-upand/or periodically throughout operation. For example, the electricalpanel may be configured to adjust the class type of a power supply afterinstallation. For instance, the a particular power supply may beinitially configured to operate as a Class 1 power supply (e.g., a HighVoltage Class 1 power supply), and later be configured (e.g., by thepanel control circuit 104) to operate as another class of power supply(e.g., as a Low Voltage Class 2 power supply provided that the properredundancy exists).

As noted herein, an electrical panel, such as the lighting panel 102,may be connected to one or more DC power sources via the DC line feed134 and/or via the battery bank feed 133. The DC power sources mayinclude any combination of an alternative energy sources, such as a PVpower supply, a wind turbine system, a hydroelectric system, a batterybank, etc. The electrical panel may include a grid-tie inverter (e.g.,or, for example, the grid-tie inverter may be connected to theelectrical panel but external to the electrical panel). The grid-tieinverter may be electrically connected between the DC line feed (e.g.,and/or the battery bank feed) and the AC line feed 132. The grid-tieinverter may be configured to receive DC power via the DC line feed,convert the DC power to AC power, and provide the AC power to the ACline feed (e.g., and ultimately to an external electrical grid). Theelectrical panel may sell a portion or all of the DC power received fromone or more DC power sources back to the electrical grid, for example,after using a portion of the DC power for powering one or moreelectrical loads. The amount or percentage of DC power sold back to theelectrical grid may be determined by the electrical panel using agrid-tie inverter control procedure.

FIG. 6 is an example of a grid-tie inverter control procedure 600performed by an electrical panel, such as the lighting panel 102. Theelectrical panel (e.g., the panel control circuit 104) may perform thegrid-tie inverter control procedure 600 continuously or periodically,for example, at scheduled times of the day, whenever an electrical loadis adjusted (e.g., turned on or off), and/or in response to an inputfrom a system administrator. At 610, the electrical panel may determine(e.g., measure) the amount of DC input power P_(DC-IN) that is receivedvia the DC line feed 134 and/or via the battery bank feed 133 from theone or more DC power sources. At 620, the electrical panel may determinethe amount of power P_(EL) requested by the electrical loads of theelectrical panel (e.g., the power supplies). The power requested by theelectrical loads P_(EL) may vary continuously, for example, in responseto other inputs into the load control system (e.g., the load controlsystem 100), such as via remote control devices, occupancy/vacancysensors, daylight sensors, etc.

The electrical panel may then determine how much DC input powerP_(DC-IN) to use versus to sell back to the electrical grid based on oneor more factors. These factors may include, but are not limited to, theamount of DC input power P_(DC-IN), the amount of power P_(EL) requestedby the electrical loads of the electrical panel, environmentalconditions, such as weather, whether the electrical panel is receivingAC input power P_(AC) (e.g., whether there is an outage), a price indexof AC input power P_(AC), the time of day, the day of the week, themonth of the year, the location of the electrical panel, etc. Forexample, at 630 of the grid-tie inverter control procedure 600, theelectrical panel may determine the factors that are associated with thesale of AC power to the electrical grid. The factors may be static ormay adjust, for example, based on settings received from a systemadministrator. The factors may also be weighted.

At 640, the electrical panel may determine to adjust (e.g., lower) thepower P_(EL) provided to one or more electrical loads (e.g., dim one ormore LED light engines 150) based on the determined factors. Theelectrical panel may determine to lower the power P_(EL) provided to theelectrical loads within a window of acceptance. For example, theelectrical panel may determine to lower the power P_(EL) such that theelectrical panel limits the amount of received AC input power P_(AC)(e.g., potentially doesn't receive any AC power). The electrical panelmay determine to lower the power P_(EL), for example, in instances wherethe price index of AC input power P_(AC) exceeds a threshold, onparticular days of the week and/or times of the day, where there is anoutage and the electrical panel isn't receiving any AC input powerP_(AC), and/or the like.

At 650, the electrical panel may determine whether to sell any DC inputpower P_(DC-IN) to back to the electrical grid. For example, if theelectrical panel determines that the amount of power P_(EL) (e.g., theadjust P_(EL)) is less than the amount of DC input power P_(DC-IN), thenthe electrical panel may sell any excess DC input power P_(DC-IN) backto the grid at 660.

If, for example, the electrical panel determines that the amount ofpower P_(EL) (e.g., the adjust P_(EL)) is equal to or exceeds the amountof DC input power P_(DC-IN), then, at 670, the electrical panel maydetermine to use all of the DC input power P_(DC-IN) to meet the requestof the loads and, to the extent necessary, also use AC input powerP_(AC). By using all of the DC input power P_(DC-IN), the electricalpanel may avoid a double conversion (e.g., converting DC input powerP_(DC-IN) to AC for sale, and converting AC input power P_(AC) to DC foruse by the electrical loads). Further, even if the electrical paneldetermines that the amount of power P_(EL) (e.g., the adjust P_(EL)) isequal to or exceeds the amount of DC input power P_(DC-IN), theelectrical panel may still determine, based on the determined factors,to store all or a portion of the DC input power P_(DC-IN) in the batterybanks via the battery bank feed 133.

Although described with reference to the LED light engines 150 and themotorized window treatments 160, one or more embodiments describedherein may be used with other electrical loads and load control devices.For example, one or more of the embodiments described herein may beperformed by a variety of load control devices that are configured tocontrol a variety of electrical load types, such as, for example, ascrew-in luminaire including a dimmer circuit and an incandescent orhalogen lamp; a screw-in luminaire including a ballast and a compactfluorescent lamp; a screw-in luminaire including an LED driver and anLED light source; a dimming circuit for controlling the intensity of anincandescent lamp, a halogen lamp, an electronic low-voltage lightingload, a magnetic low-voltage lighting load, or another type of lightingload; an electronic switch, controllable circuit breaker, or otherswitching device for turning electrical loads or appliances on and off;a plug-in load control device, controllable electrical receptacle, orcontrollable power strip for controlling one or more plug-in electricalloads (e.g., coffee pots, space heaters, other home appliances, and thelike); a motor control unit for controlling a motor load (e.g., aceiling fan or an exhaust fan); a drive unit for controlling a motorizedwindow treatment or a projection screen; motorized interior or exteriorshutters; a thermostat for a heating and/or cooling system; atemperature control device for controlling a heating, ventilation, andair conditioning (HVAC) system; an air conditioner; a compressor; anelectric baseboard heater controller; a controllable damper; a humiditycontrol unit; a dehumidifier; a water heater; a pool pump; arefrigerator; a freezer; a television or computer monitor; a powersupply; an audio system or amplifier; a generator; an electric charger,such as an electric vehicle charger; and an alternative energycontroller (e.g., a solar, wind, or thermal energy controller). Alighting panel 102 may be coupled to and/or adapted to control multipletypes of electrical loads in a load control system.

1. An electrical control panel for controlling a plurality of electricalloads, the control panel comprising: a control circuit; a plurality ofpower supplies, where each power supply is configured to receivealternating current (AC) power and output direct current (DC) power; anda plurality of control modules, wherein more than one control module isassociated with each of the plurality of power supplies; and wherein acontrol module of the plurality of control modules is configured toreceive DC power from the associated power supply, and configured toprovide a DC voltage comprising a digital message to at least oneelectrical load over a two-wire link.
 2. The control panel of claim 1,wherein a subset of the electrical loads each comprise a respectiveaccessory module associated with a control module.
 3. The control panelof claim 2, wherein the associated control module and accessory moduleoperate in tandem to provide proper power for operation and control ofthe corresponding electrical load.
 4. The control panel of claim 1,wherein the digital message comprises a command for controlling the atleast one electrical load.
 5. The control panel of claim 1, wherein thecontrol circuit is configured to provide a report relating to at leastone of the operation and configuration of the control panel.
 6. Thecontrol panel of claim 1, wherein the control circuit is configured toreceive a configuration from a remote entity relating to at least one ofthe operation and configuration of the control panel.
 7. The controlpanel of claim 1, wherein the control module is configured to providethe DC voltage and the digital message to the at least one electricalload over the link via an accessory module.
 8. The control panel ofclaim 7, wherein the control module is configured to receive a responsedigital message from the accessory module.
 9. The control panel of claim1 wherein the DC voltage includes a pulse-width modulated (PWM) DCvoltage in which each pulse includes a leading data edge and a trailingreference edge such that a temporal duration existent between thetrailing reference edge and the leading data edge of successive PWMpulses defines an offset time period.
 10. The control panel of claim 9wherein the offset time period comprises a variable temporal durationoffset time period, the temporal duration of the offset time perioddetermined, at least in part, on a demand presented by one or more ofthe plurality of electrical loads.
 11. The control panel of claim 9wherein the digital message includes one or more data bits based on atemporal duration of each respective one of a plurality of offset timeperiods.
 12. The control panel of claim 11 wherein the digital messageincludes one or more data bits based on respective durations of aplurality of successive offset time periods.
 13. The control panel ofclaim 11 wherein the temporal duration of each of the plurality ofoffset time periods corresponds to a unique data bit sequence.
 14. Thecontrol panel of claim 11 wherein the plurality of offset time periodsconsist of four offset time periods, each having a different temporalduration, and the data bits consist of a unique two data bit sequencedetermined by the duration of respective ones of the four offset timeperiods.
 15. A control module couplable to an AC/DC power supplydisposed in a modular distribution panel, the control module to:generate a pulse-width modulated (PWM) DC signal, each pulse in the PWMsignal including a leading data edge and a trailing reference edge suchthat a temporal duration existent between the trailing reference edgeand the leading data edge of successive PWM pulses defines an offsettime period; associate a unique data bit sequence with each respectiveone of a plurality of offset time periods, each of the offset timeperiods having a different temporal duration; and selectively adjust thetemporal duration of at least one of the plurality of offset timeperiods to communicate a digital message that includes one or more databit sequences from the control module to an electrical load coupled tothe control module.
 16. The control module of claim 15, the controlmodule to further: generate a digital message that includes a pluralityof data bit sequences, each of the plurality of data bit sequences basedon the temporal duration of each respective one of a plurality of offsettime periods.
 17. The control panel of claim 16 wherein the digitalmessage includes data based on the temporal duration of each respectiveone of a plurality of successive offset time periods.
 18. The controlpanel of claim 16 wherein the temporal duration of each of the pluralityof offset time periods determines the unique data bit sequence.
 19. Thecontrol panel of claim 15 wherein the plurality of offset time periodsconsists of four offset time periods, each having a different duration,and the one or more data bits consist of a unique two data bit sequencedetermined by the duration of respective ones of the four offset timeperiods.
 20. A non-transitory, machine-readable, storage device thatincludes instructions that when, when executed by a control modulecoupled to an AC/DC power supply, cause the control module to: generatea pulse-width modulated (PWM) DC signal, each pulse in the PWM signalincluding a leading data edge and a trailing reference edge such that atemporal duration existent between the trailing reference edge and theleading data edge of successive PWM pulses defines an offset timeperiod; associate a unique data bit sequence with each respective one ofa plurality of offset time periods, each of the offset time periodshaving a different temporal duration; and selectively adjust thetemporal duration of at least one of the plurality of offset timeperiods to communicate a digital message that includes one or more databit sequences from the control module to an electrical load coupled tothe control module.
 21. The non-transitory, machine-readable, storagedevice of claim 20 wherein the machine-readable instructions furthercause the control module to: generate a digital message that includes aplurality of data bit sequences, each of the plurality of data bitsequences based on the temporal duration of each respective one of theplurality of offset time periods.
 22. The non-transitory,machine-readable, storage device of claim 21 wherein themachine-readable instructions that cause the control module to generatethe digital message that includes the one or more data bit sequencesbased on the temporal duration of each respective one of the pluralityof offset time periods further cause the control module to: generate adigital message includes the one or more data bit sequences based on thetemporal duration of each respective one of a plurality of successiveoffset time periods.
 23. The non-transitory, machine-readable, storagedevice of claim 21 wherein the machine-readable instructions that causethe control module to associate the unique data bit sequence with eachrespective one of the plurality of offset time periods further cause thecontrol module to: determine the unique data bit sequence based on theduration of each respective one of the plurality offset time periods.24. The non-transitory, machine-readable, storage device of claim 21wherein the instructions that cause the control module to associate theunique data bit sequence with each respective one of the plurality ofoffset time periods, further cause the control module to: associate aunique data bit sequence with each of four offset time periods, each ofthe four offset time periods having a different temporal duration, andin which the one or more data bits consist of a unique two data bitsequence determined by the temporal duration of respective ones of thefour offset time periods.